Although worn, this mark is recognizable as that of the important silversmith Jean-Charles Cahier. The mark is described (although not illustrated) in Arminjon 1798-1838, mark 1671: J.C.C. underneath the Hebrew letters for “Jehovah”. (The horizontal line above the Latin letters is the giveaway.) If you do an internet search for Jean Charles Cahier, you will find many references to him; see here, for instance:
A Treasury of Silverware of Jean Charles Cahier, Goldsmith to the King. (An internet search will also reveal images of the complete mark, but as most of these are commercial, I can't post them here.)
Jean Charles Cahier
Born: ca. 1772, Soissons, Aisne, son of Edme Cahier & Marie Peron
Married: 24 Nov 1802, to Adelaïde Gabrielle Louis Rallot
Died: 17 Oct 1857, Marseille, Bouches-du-Rhône
Cahier was trained in the workshop of the famous Martin-Guillaume Biennais, which he took over in 1821 after Biennais’ retirement. Cahier was appointed silversmith to both Restauration monarchs, Louis XVIII and Charles X. One record states that he was bankrupted in in 1828, but he clearly continued to operate until around 1849, when his workshop was assumed by Rénaud-Placide Poussielgue-Rusant.
Very nice find! Cahier is among the top tier of 19th century French makers.